This invention relates to thermal indicators used on smoking articles. More particularly, this invention relates to thermal indicators embodied as waxes or other compounds which melt away to reveal colored substrates, or use microencapsulated chemicals, to indicate a predetermined temperature within the smoking article.
There are non-combustion smoking articles currently on the market that provide an alternative to conventional tobacco-burning smoking articles. Non-combustion smoking articles include smoking articles heated by electrical or chemical means, or by burning some type of heat source other than the tobacco itself. The tobacco or flavor source is heated, but is not burned. If the heat source is contained within the non-combustion smoking article, it provides no visual indication, such as a burning end, of the temperature gradient along the article. A smoker is unable to determine which portion of the smoking article is hot.
A person smoking a non-combustion smoking article must be informed that the device has begun to work. The smoker also needs information about the on-going operation of the device, for example, whether the heat source is still operating. Finally, the smoker must know when to stop puffing because the flavor or heat source is expended. Unless the smoker knows this, the smoker may try to use the device longer than is intended by the manufacturer, possibly resulting in customer dissatisfaction.
The thermal indicators used on smoking articles must not affect the flavor or safety of the smoking articles. The indicator materials must be non-toxic both prior to and after heating.
In view of the foregoing, it is an object of this invention to provide non-toxic thermal indicators for use on non-combustion smoking articles.
It is another object of this invention to provide a method for showing the internal thermal status of a non-combustion smoking article along its length.